1. Openings in walls
Structural integrity and weather
exclusion

2. Wall openings
• Potential source of major problems
– The opening weakens the wall
– The wall above the opening can fall down
into it
– Rain can get in around the edges of the
opening
• But we have to have them
– To get in and out
– To let light and air in
– To define the character of
the building…

3. Openings crucial to building appearance

4. Modern architecture uses openings too

5. Dealing with structural problems
• Openings in walls create two structural
problems
– Support for the wall above the opening
– Retaining the integrity of the wall
• Problems almost non-existent in timber
framed walls
• The problems
are dominating in
masonry walls…

6. Making a masonry opening

7. Making a masonry opening

8. Beam over opening: called a lintel

9. Simple reinforced concrete lintels
Simple, robust, heavy

10. Masonry with lintel architecture: “trabeated” architecture
UK
UAE
The simplest and most
universal architectural motif,
an opening with a beam across
the top.

11. Arch over opening
Keystone
Vousoirs

12. The city of arches, Krakow: “arcuated” architecture

13. Historical architecture
• Greek architecture: trabeated, structurally limited
• Roman architecture: arcuated, structurally open

14. Ancient historical architecture
Stonehenge: about 4,500 Ctesiphon: about 1,700 years old
years old
• Stonehenge: ultimate trabeated structure
• Ctesiphon: oldest and still the biggest brick
arch in the World

15. Arches want to spread out flat

16. Arches want to spread out flat

17. Arches want to spread out flat

18. Arches want to spread out flat

19. Ties and buttresses

20. Retaining the structural integrity of the wall

21. Retaining the structural integrity of the wall
Opening < 1/3
wall length

22. Keeping the rain out
lintels
Forming opening
breaks the cavity

23. Keeping the rain out
Rain penetrating above
the opening gets into
lintels the window frame
Forming opening
breaks the cavity

24. Keeping the rain out
Rain penetrating above
the opening gets into
lintels the window frame
Rain must be guided to
the outside by a DPC
above the lintel
Forming opening
breaks the cavity

25. Cavity tray above simple lintels
Sloped DPC over
head of lintel
called a cavity tray
It guides any water
in the cavity to the
outside

26. Cavity tray above simple lintels
Sloped DPC over
head of lintel
called a cavity tray
It guides any water
in the cavity to the
outside

27. Cavity trays
Cavity tray
Dam stops water
opening
pouring off end of tray
Cavity tray can be formed from lead,
sheet plastic or specially made for the job

28. Specially formed steel lintels
Steel lintel, filled with expanded
polystyrene for insulation,
shaped to direct water to the
outside

29. Speciality lintels
DPC cavity tray
“Arched” lintels
The lintel is not necessary
structurally, but it provides a former
for the arch and supports a cavity
tray

30. Side of opening must be closed
Cut brick, mortar,
flexible DPC. Common
but difficult
Plan view of one side of an opening

31. Side of opening must be closed
Cut brick, mortar,
flexible DPC. Common
but difficult
Prefabricated plastic,
insulated cavity reveal
closer. Very effective
Plan view of one side of an opening

32. References
• CHUDLEY, R. ; GREENO, R. (2010).
Construction technology. 6th ed.
Pearson Education.
• CHUDLEY, R. ; GREENO, R. (2006).
Building construction handbook. 6th
ed. Butterworth-Heinemann.
• Suppliers of lintels, cavity tray and
cavity closers:
– Cavity trays: http://www.cavitytrays.co.uk/
– Steel lintels: http://www.catnic.com/